A device for testing or examining the presence of one or a plurality of substance(s) in a liquid sample, for example, urine or a blood sample is referred to as a diagnosis kit or a measuring cartridge. To be specific, current diagnostic fields are being integrated into point-of-care testing (POCT). The POCT is defined as medical testing that is conducted outside a central testing room and can be performed even by ordinary people having no special skill or knowledge. At present, a diagnostic area of the POCT is spread to an individual at a site as well as a hospital.
For example, the POCT may be applied to examine the quantity of antibiotics in blood by taking a small quantity of blood after a large dose of antibiotics are administered to a patient in a hospital so as to prevent infection, or may be applied to rapidly examine a kind of medicine taken in a body so as to guarantee appropriate treatment in the case of an unexpressive child or a patient who takes a massive dose of medicine because of cognitive impairment.
An example of a medical instrument or a measuring instrument making a diagnosis using the diagnosis kit includes an electrochemical blood analyzer, an optical blood analyzer, a measuring instrument using a magnetic-field measuring method, etc. The electrochemical blood analyzer is operated so that it draws a voltage, a current, and a resistance from the measuring cartridge and uses the values for measurement. The optical blood analyzer is operated so that it acquires an image of a test line of the measuring cartridge and measures a pixel intensity of the acquired image.
FIG. 1 is a conceptual view illustrating a sensing principle of a magnetic resistance sensor. For the convenience of description, the sensing principle will be described with reference to a giant magnetoresistance (GMR) sensor as an example of the magnetic resistance sensor. This shows a spin-valve type GMR device. As shown in the drawing, the magnetic resistance sensor is configured such that a non-magnetic metal layer is fitted between two ferromagnetic metal layers. Magnetism of the first ferromagnetic metal layer is fixed, and magnetism of the second ferromagnetic layer is variably adjusted, so that only electrons having spin oriented in a specific direction pass through a conductor when the magnetism of the second layer is parallel to that of the first layer. That is, there occurs a difference in electric potential or electric resistance induced in material depending on the magnetization directional alignment between the two ferromagnetic layers, and the difference is detected as a digital signal. The GMR device has a conductor as an interlayer material. The diagnosis instrument using the magnetic resistance sensor is a high sensitive POCT device capable of quantitatively measuring magnetic particles accumulated in a lateral flow membrane using the GMR sensor.
Such a measuring instrument using magnetic resistance requires greater automation, and needs to be implemented as standardized automatic equipment to improve a quantitative measuring quality.